This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A204039 #7 Jul 22 2025 17:43:45 %S A204039 16,44,44,121,164,121,286,603,603,286,676,1758,2928,1758,676,1482, %T A204039 5130,10505,10505,5130,1482,3249,13040,37642,44366,37642,13040,3249, %U A204039 6840,33223,111578,189580,189580,111578,33223,6840,14400,77574,330509,642272 %N A204039 T(n,k)=Number of (n+1)X(k+1) 0..1 arrays with the sums of 2X2 subblocks nondecreasing rightwards and downwards. %C A204039 Table starts %C A204039 ...16....44....121.....286......676......1482.......3249.......6840.......14400 %C A204039 ...44...164....603....1758.....5130.....13040......33223......77574......181559 %C A204039 ..121...603...2928...10505....37642....111578.....330509.....863435.....2254026 %C A204039 ..286..1758..10505...44366...189580....642272....2198077....6415866....18855400 %C A204039 ..676..5130..37642..189580...969528...3811097...15164049...50226272...167435933 %C A204039 .1482.13040.111578..642272..3811097..16895850...76619720..282617310..1055589853 %C A204039 .3249.33223.330509.2198077.15164049..76619720..397550036.1650280817..6940548943 %C A204039 .6840.77574.863435.6415866.50226272.282617310.1650280817.7576693894.35441648714 %H A204039 R. H. Hardin, <a href="/A204039/b204039.txt">Table of n, a(n) for n = 1..364</a> %e A204039 Some solutions for n=4 k=3 %e A204039 ..1..0..1..1....1..0..0..1....0..1..0..1....0..1..1..0....1..0..0..0 %e A204039 ..0..1..1..0....0..0..1..0....1..0..1..0....1..0..0..1....0..1..1..1 %e A204039 ..1..0..1..1....1..1..0..1....0..1..1..1....0..1..1..1....1..0..1..1 %e A204039 ..0..1..1..1....0..1..1..1....1..0..1..1....0..1..1..1....1..1..1..1 %e A204039 ..0..1..1..1....1..1..0..1....0..1..1..1....0..1..1..1....1..1..1..1 %K A204039 nonn,tabl %O A204039 1,1 %A A204039 _R. H. Hardin_ Jan 09 2012